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Desmoid tumours in people with an APC fault | CION Cancer Clinics
A desmoid tumour is a firm growth of scar-like tissue that some people with an APC fault develop, most often in the tummy after bowel surgery. It does not spread to other organs the way a cancer does, but it can press on what lies around it. This page explains who is more likely to get one, how it is found, and why doctors often watch before treating. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What is a desmoid tumour, and is it a cancer?
- Which APC carriers are more likely to get a desmoid?
- What happens once a desmoid is found?
- Which words will you see on a desmoid scan report?
- Does it matter where the desmoid is?
- What this page cannot tell you
- Four things families believe about desmoids, and what is true
- Common questions about desmoid tumours in FAP
The short answer
What is a desmoid tumour, and is it a cancer?
A desmoid tumour is a firm lump made of the tissue the body uses to heal wounds. It does not spread to the liver, lungs or bones the way a cancer does. It can still grow into the tissue around it, which is why doctors take it seriously in people who carry an APC fault.
Why it is linked to APC
The APC gene acts as a brake on cell growth in many tissues, not only the bowel lining. When one copy is faulty from birth, the cells that lay down scar tissue can also lose their brake. In most people with FAP this never happens. In a minority, a desmoid forms, most often inside the tummy.
Why it matters more than its name suggests
Once the large bowel has been removed, bowel cancer risk falls sharply. Desmoids then become one of the main health problems that remain. A desmoid inside the tummy can press on the bowel, the tubes from the kidneys or the blood vessels that feed the gut. Most do not cause that kind of trouble, but the few that do need specialist care.
A desmoid is not bowel cancer coming back. It is a different kind of growth with a different plan.Who is more likely
Which APC carriers are more likely to get a desmoid?
No one can predict a desmoid for certain. Four things are known to tilt the odds, and your team will ask about each.
Where the fault sits in the gene
APC is a long gene. Faults towards its far end are linked to more desmoids than faults near the start. Your report names the exact change, and a counsellor can tell you which part of the gene it falls in.
A relative who had one
Desmoids tend to cluster in families. If a parent, brother or sister with the same fault developed a desmoid, your own chance is higher than for a carrier with no such history.
Tell your surgeon about any relative's desmoid before bowel surgery is planned.Surgery on the tummy
Many desmoids appear within a few years of bowel surgery. Healing tissue seems to act as a trigger. This is one reason the timing and type of preventive surgery is weighed so carefully.
Pregnancy and hormones
Some desmoids appear or grow during or soon after pregnancy. This does not mean a woman with FAP should avoid pregnancy.
What it does mean
- Plan a pregnancy with your team
- Report any new lump in the tummy wall
- Expect closer checks in the year after birth
Not sure whether this applies to you?
Ask an oncologistAfter it is found
What happens once a desmoid is found?
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A scan to measure it
A CT or MRI scan shows the size of the desmoid and what it sits next to. This first picture becomes the baseline that every later scan is compared with.
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A period of watching
Many desmoids stay the same size for years, and some shrink on their own. If yours is small and causing no trouble, the usual first step is repeat scans rather than treatment. Watching is a plan, not neglect.
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Tablets if it grows or hurts
If the desmoid grows or causes pain, the first treatment is often a pair of tablets: a painkiller of the anti-inflammatory type and a hormone-blocking medicine. They are gentle compared with other options and suit long-term use.
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Stronger treatment if needed
A desmoid that keeps growing may need low-dose chemotherapy or a targeted tablet. These are chosen by a medical oncologist who treats soft-tissue tumours, after discussion with the surgeon.
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Surgery only in selected cases
A desmoid in the tummy wall can sometimes be removed cleanly. One deep inside the tummy often grows back after surgery, so operating is usually kept for emergencies such as a blocked bowel.
On your report
Which words will you see on a desmoid scan report?
- Desmoid tumour
- A growth of scar-like tissue. It can grow into nearby tissue but does not spread to distant organs.
- Aggressive fibromatosis
- Another name for the same thing. Aggressive describes how it grows locally, not that it is a cancer.
- Mesentery
- The fan of tissue that holds the bowel in place and carries its blood supply. It is the most common site for a desmoid in FAP.
- Abdominal wall
- The layers of muscle at the front of the tummy. Desmoids here are easier to see, feel and treat.
- Active surveillance
- Planned repeat scans with no treatment unless the desmoid changes. It is a recognised first choice for many desmoids.
- Desmoid precursor lesion
- A flat patch of scar-like tissue seen during surgery or on a scan. It may or may not ever become a lump.
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Does it matter where the desmoid is?
In the tummy wall
Deep inside the tummy
Often felt as a firm lump under the skin
Usually found on a scan or because of pain
Rarely presses on anything important
Can press on the bowel, kidney tubes or blood vessels
Surgery is sometimes a reasonable choice
Surgery is avoided where possible
Watching or tablets often enough
Needs a team used to treating desmoids
Being straight with you
What this page cannot tell you
It cannot tell you whether you will develop a desmoid. That depends on your exact APC change, your family history and the surgery you have had or are planning. What your specific variant means is a question for the counsellor who ordered the test.
It cannot choose your treatment
Desmoids are uncommon, and the evidence comes from small studies. Specialists do not always agree on when to treat and with what. A plan made by a team that has seen many desmoids is worth the extra travel from a district town to Hyderabad.
Who this does not apply to
Most people with FAP never develop a desmoid, and this page does not apply to the far larger group who have ordinary bowel polyps with no inherited fault. A lump in the tummy wall in someone without FAP is far more likely to be something else, such as a hernia.
If you have a scan report that mentions fibromatosis, bring it and your APC report to the same appointment.Commonly believed
Four things families believe about desmoids, and what is true
"A desmoid means the cancer has spread."
It does not. A desmoid is a separate kind of growth that stays where it starts. It is not a sign that bowel cancer has returned or reached another organ.
"Any lump must be cut out at once."
For many desmoids, especially deep inside the tummy, surgery can trigger faster regrowth. Watching or tablets are often the safer first steps, and some desmoids shrink with no treatment at all.
"Because desmoids follow surgery, bowel surgery should be refused."
Preventive bowel surgery is still what stops bowel cancer in FAP. Desmoid risk can change how and when it is done, but it is rarely a reason to skip it. That decision belongs with your surgeon.
"If my father had one, I will get one too."
A family history raises the chance, but it does not make a desmoid certain. Many relatives in such families never develop one. It does mean your team should know about it early.
Questions we are asked
Common questions about desmoid tumours in FAP
Can a desmoid tumour kill you?
Most desmoids do not threaten life, and many stay the same size for years. A small number deep inside the tummy grow large enough to block the bowel or its blood supply, and those can be serious. That is why a desmoid in someone with FAP is watched by a specialist team rather than ignored.
What symptoms should make me go to hospital the same day?
Repeated vomiting, a swollen tight tummy, and being unable to pass stool or wind together suggest a blocked bowel. Go to the nearest emergency department and tell them you have FAP and a desmoid. Do not wait to see whether it settles overnight.
Will the desmoid come back after surgery?
Desmoids deep inside the tummy often do grow back after being removed, which is why surgery is not the usual first choice for them. Desmoids in the tummy wall are more likely to stay away after a clean removal. Your surgeon will explain which situation applies to you.
Are the tablets safe to take for a long time?
The first-line tablets are usually taken for many months, with regular blood tests and check-ups. Anti-inflammatory painkillers can irritate the stomach and affect the kidneys, so they are monitored. Never start or stop them on your own. Your oncologist will balance the benefit against the side effects.
Can I get pregnant if I have FAP and a desmoid?
Many women with FAP have healthy pregnancies, including some with a desmoid. Pregnancy can make a desmoid grow, so it is best planned with your oncologist and obstetrician together. Expect a scan before and after, and report any new lump or pain in the tummy wall.
Does every APC carrier need scans for desmoids?
Not usually. Routine scans for desmoids are mainly offered to carriers at higher risk, such as those with a family history of desmoids or a fault in the part of the gene linked to them. Everyone else is checked if symptoms or a lump appear.
Is a desmoid the same as Gardner syndrome?
Gardner syndrome is an older name for FAP when it comes with growths outside the bowel, such as bony lumps, skin cysts and desmoids. Today it is seen as part of the same APC condition, not a separate illness. The care plan is the same.
Are desmoids covered by Aarogyasri or insurance?
Scans, surgery and some treatments for a desmoid may be covered, depending on the scheme and the policy. Cover for long-term tablets varies. Ask for a written estimate and check it against your policy or scheme card before treatment starts, not afterwards.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- GeneReviews (NCBI) — APC-Associated Polyposis Conditions
- MedlinePlus Genetics — Familial adenomatous polyposis
- National Cancer Institute — Genetics of Colorectal Cancer (PDQ)
- MedlinePlus Genetics — Desmoid tumor
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Extra-colonic features: teeth, eyes and boneThe other signs of APC outside the bowelDeciding the timing of preventive bowel surgeryHow desmoid risk shapes when surgery happensAPC mutation: which cancers and what riskEvery organ an APC fault can affectSurveillance for APC carriersWhich checks happen, and roughly when
Talk to us
Has a scan mentioned a desmoid or fibromatosis?
Send us the scan report and your APC result. We will help you reach a team that treats desmoids and explain the options in plain language. One helpline serves every CION centre.